Mitsubishi Electric QJ71MT91 User Manual page 44

4 MODBUS STANDARD FUNCTIONS
Function Code
(Sub Code)
01 Read coils
02 Read discrete inputs
03 Read holding registers
04 Read input registers
05 Write single coil
06 Write single register
07 1 2 Read exception status
08 1 2 Diagnostics
Get communications event
11 1 2
counter
4
12 1 2 Get communications event log
15 Write multiple coils
16 Write multiple registers
17 1 2 Report slave I.D
20(6) Read file record
21(6) Write file record
22 Mask write register
23 Read/write multiple registers
24 1 Read FIFO queue
43 1 Read device identification
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(2) Standard function support list by master and slave functions
The following table indicates a standard function support list classified by the
master and slave functions of the QJ71MT91.
Automatic
Function
communication
1: The QJ71MT91 slave function does not support this function.
However, it can be issued from the master (QJ71MT91) by use of the MBREQ instruction.
2: The function codes 07, 08, 11, 12 and 17 are the functions dedicated to the MODBUS serial
protocol.
3: For details of the function codes for the master function, refer to the explanation of the
corresponding function.
4: The dedicated instructions are unavailable for the QJ71MT91 mounted on a MELSECNET/H
remote I/O station.
5: This function has a limit in the slave function when the QJ71MT91 is mounted on a
MELSECNET/H remote I/O station.
An exception response will result if a device unsupported by the MELSECNET/H remote I/O
station is assigned as a MODBUS device and an access request is made from the master
station.
In this case, an error code will be stored into the error log of the QJ71MT91, and an exception
code will be returned to the master.
6: This function is not supported when the QJ71MT91 is mounted on a MELSECNET/H remote I/O
station.
Master Function
MBRW instruction
4
function
MELSEC-Q
3
MBREQ Slave Function
4
instruction
: Supported :Not supported
5
5
5
5
5
5
5
5
6
6
5
5
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